Studies of graphite and graphene as next-generation switching materials have begun all over the world. This is because graphite and graphene has the possibility to be far higher in the mobility than that of silicone and because these are carbon materials and therefore could be ecological materials.
For example, “Electric Field Effect in Atomically Thin Carbon Films”, by K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov in Science Vol. 306, p. 666, 2004; and “Fabrication and electric-field-dependent transport measurements of mesoscopic graphite devices”, by Yuanbo Zhang, Joshua P. Small, William V. Pontius, and Philip Kim, in Applied Physics Letters, Vol. 86, 073104, 2005 report the carrier concentration inside a graphite thin film, using an SiO2 thin film on an Si substrate as a gate insulating film. The devices described in these references have some problems in that, since the substrate serves as a gate electrode, the gate could not accept independent operation for individual devices and that, since the SiO2 insulating film is thick, a large gate voltage (about 100 V) is needed.
“Transport Measurements Across a Tunable Potential Barrier in Graphene”, by B. Huard, J. A. Sulpizio, N. Stander, K. Todd, B. Yang, and D. Goldhaber-Gordon, in Physical Review Letters, Vol. 98, 236803 (2007) reports formation of a polymethyl methacrylate (PMMA) resin film on a graphite thin film by coating thereon as a top gate insulating film for potential control inside the graphite thin film. However, this is troublesome in that PMMA must be applied and crosslinked through exposure to electronic beam, and in addition, since the insulating film is 40 nm and is not sufficiently thin, the gate voltage reducing effect is insufficient.